In the field of HDD (Hard Disk Driver), development of highly sensitive head for data reading has been continued and the TMR (Tunneling Magneto-Resistive) head and CPP-(GMR (Current Perpendicular to Plane Giant Magneto-Resistive) head are listed as the typical examples of the head for the next generation. As an example of a read amplifier for amplifying the signals of GMR read head, a circuit illustrated in FIG. 10 has been proposed in the Non-Patent Document 1.
Moreover, in the field of the HDD, efforts have been made for improvement in area density and the perpendicular recording for magnetizing media in the perpendicular direction will be put into practical use in near future. A read amplifier for amplifying the signals from the read head for perpendicular recording has been disclosed, for example, in the Non-patent Document 2.
[Non-Patent Document 1]
“A 0.55 nV/√Hz Gigabit Fully-Differential CMOS Preamplifier for MR/GMR Read Application” ISSCC Digest of Technical Papers, pp. 64–65, February 2002.
[Non-Patent Document 2]
“A 1 Gb/s Read/Write Preamplifier for Hard-Disk-Drive Application”, Digest of technical paper of ISSCC 2001, 2001, 00. 188–189.